1. Field of the Invention
The present invention relates to prosthetics and, more particularly, to an anchoring system for post-operative prosthetic devices for above-the-knee amputation patients.
2. Description of the Background
There are a variety of different types of prosthetic devices for patients that have had either transfemoral (above-knee) or transtibial (below the knee) amputation. Typically, post-operative prosthetic devices for either type of amputation patients begin with a liner, which is rolled on to the residual limb. The liner is a soft, stretchy material that acts as an interface with the prosthetic.
Once the liner is on, the residual limb then slides into a hard socket. This socket is specially made to fit and can be made out of a variety of materials.
The hard socket for a transfemoral prosthesis has a knee joint connected to it, and the more fluid and natural the movement of the knee the better. Transtibial prosthetics have no knee joint. In both cases (with or without a knee joint) there typically is an aluminum or carbon fiber tube to which a foot module is connected.
For example, FIG. 1 is a prior art perspective view of the prosthetic device set forth in U.S. Pat. No. 5,653,766 to Naser issued Aug. 5, 1997. The illustrated prosthetic device 20 includes a generally cylindrical socket 24 having an opening for receiving an amputated limb. The socket 24 is closed at the other end, and is mounted on a bendable knee joint. Once the limb is properly received within the socket 24, straps 38 are adjusted so that a secure fit is achieved. The patient then is able to walk using the prosthetic device 20.
With all transfemoral and/or transtibial prosthetics (above and below the knee), it is very important that the socket be securely fitted to the limb and secured in place. Stability is a common problem as many existing anchoring systems use a single attachment point to hold the residual limb in place, and this typically leads to extraneous pivoting, rotation and shift during ambulation. Moreover, it is important to be able to easily adjust the anchoring system periodically inasmuch as the mass of the limb may change significantly over the course of a day. Consequently, there should be some means for adjustment on the fly. The above-referenced ""766 patent uses a radial pressure-fit imposed by tightening two belts. However, this tends to squeeze the limb and adds to discomfort, Moreover, the radial pressure tends to pop the limb out of the socket over the course of a day.
The well-known ICEX Socket System uses a lanyard kit as a docking and locking mechanism. The socket has a distal pin that docks with the prosthesis. A lanyard is connected to the liner through a slot in the bottom of the socket. The lanyard is pulled to allow the patient""s residual limb, which is enclosed in the silicone liner, to be drawn into the socket by the lanyard. The lanyard is then anchored to the front of the socket. The lanyard has the advantage of allowing for adjustment of position within the ICEX Socket. If the limb changes position because of volume change and the distal migration of the limb into the socket, the prosthesis can easily be adjusted by the lanyard to compensate. The lanyard method of donning the socket also significantly reduces pain directly related to the donning process with a pin-locking mechanism. However, it has been found that many amputees lack thee room for, are unable to tolerate, or have difficulty engaging the distal pin. Others complain of pain associated with engagement of the pin.
Coyote Systems(copyright) sells the Summit Lock for those who cannot tolerate the xe2x80x9cpullxe2x80x9d associated with distal pin lock and lanyard suspension methods. The Summit Lock eliminates the pin, and instead uses a ratchet-type ski buckle assembly (a strip with multiple lock teeth), which is attached to
the lateral aspect of the liner at about ischial level. The tab is fed through a hole in the socket and engages in the externally mounted lock. Positioning the tab through the socket wall controls rotation. Mounting the lock externally makes it easy to engage and reduces jamming. While the Summit Lock is a more flexible design, it does not provide as secure a fit. The Summit Lock only holds the limb in place from the top of the socket and is prone to shift. In addition, the patient cannot tighten the fit of the liner in the socket from a sitting position but must put his/her full weight onto the prosthetic.
There remains a significant commercial need for a prosthetic anchoring system which provides a stable anchor for the liner with topside and lower attachment which prevents all extraneous up and down motion, pivoting, rotation and shift during ambulation, and which allows a patient to easily tighten/readjust the fit of the liner in the socket from a sitting position.
Accordingly, it is an object of the present invention to provide a prosthetic anchoring system which increases the stability of the liner anchor using a combination of top-side and lower attachments to prevents all extraneous up and down motion, pivoting, rotation and shift.
It is another object to eliminate the need for distal pin locks, and yet allow a patient to easily anchor the liner in the socket, and to easily readjust/tighten the fit of the liner in the socket from a sitting position.
It is still another object to provide a prosthetic anchoring system which is simple, inexpensive and highly effective, and which allows extremely convenient on-the-fly adjustment of the limb/liner seating to improve the fit despite changes in the size of the limb over the course is of a day.
In accordance with the foregoing object, the present device comprises an anchoring system for a transfemoral and/or transtibial prosthesis, comprising a liner for enveloping an amputee limb. The liner has a buckle suspended toward the upper end, and a corresponding strap fixedly attached on the bottom end of the liner. The anchoring system also includes a containment socket for seating the liner. The containment socket has a pair of slots there through at positions corresponding to the buckle and strap of the liner, respectively. To apply the anchoring system, the patient first applies the liner to his/her limb. The liner is then inserted into the socket with the fastening strap and buckle protruding out through the respective slots. The fastening strap is then threaded up through the buckle (running upward along the side of the socket) and are inserted there through. The patient pulls down on the strap and it works by pulley action to draw the liner down into the socket until the liner is securely seated in the socket. When fully seated, the fastening strap is secured to itself by Velcro.
The foregoing forms a suspension which holds the prosthesis on. Moreover, the fastening straps through slots absolutely prevent lateral shift as well as rotation. On the other hand, the patient need only readjust the Velcro closure to ad just the position of the limb within the socket. Thus, if the limb changes position because of volume change and the distal migration of the limb into the socket, the prosthesis can easily be adjusted to compensate.